Can this SD-1 mod be done?

[Ricey]

I tried the Fulltone mod on my SD-1.  I have another stock SD-1 that I compared it to and must confess that I prefer the stock tone to the modded tone.  I like the basic tone of the stock SD-1, but am looking or a few improvements:

1.  Overall, slightly wider Dynamic range
2.  Slightly Deeper, yet tight Bass response
3.  Ability to dial in at least a bit more gain at the far end of the spectrum, while still achieving clean boost at low end
4.  Quieter (less hiss and buzz) under high gain
5.  No mid boost "hump"-I prefer the stock SD-1 mid response.
6.  A bit smoother sound than stock would be nice, but not totally baby's butt (sterile) smooth.

In general, I like a crunchy, tight "British" style OD with lots of bite (but not icepick in the ears) that is not fizzy, buzzy, or fuzzy, or overly mid heavy with lots of attack (not compressed).

Does this mod exist?

BTW, I also did the SD-1 bypass bleed through mod along with the Fulltone Mod and that did work out great!  Thanks...

[brian wampler]

I tried the Fulltone mod on my SD-1.  I have another stock SD-1 that I compared it to and must confess that I prefer the stock tone to the modded tone.  I like the basic tone of the stock SD-1, but am looking or a few improvements:

1.  Overall, slightly wider Dynamic range
2.  Slightly Deeper, yet tight Bass response
3.  Ability to dial in at least a bit more gain at the far end of the spectrum, while still achieving clean boost at low end
4.  Quieter (less hiss and buzz) under high gain
5.  No mid boost "hump"-I prefer the stock SD-1 mid response.
6.  A bit smoother sound than stock would be nice, but not totally baby's butt (sterile) smooth.

In general, I like a crunchy, tight "British" style OD with lots of bite (but not icepick in the ears) that is not fizzy, buzzy, or fuzzy, or overly mid heavy with lots of attack (not compressed).

Does this mod exist?

BTW, I also did the SD-1 bypass bleed through mod along with the Fulltone Mod and that did work out great!  Thanks...

Yes, it sure can exist...I would do these changes:
R5: 1K
D4: LED
C3: .47uf
R6: 2.2k or 1.5k if you need less bass

OTHER OPTIONS FOR FULLER SOUND:
C4: .047 or .022uf
c5: .1uf
R9: 47k


Hope that helps!

Brian

[Kcollins]

sounds like the cuervo or blues mod would've been more what you were looking for.

[Ricey]

Brian:

Over on Monte Allum's site, he states that the chip in the stock SD-1 is a JRC4558DD, which he asserts is a cheaper version of the JRC4558D found in a Tubescreamer.  Is this true?  If so, what would be the effect on the mod you recommended above if I also  switched out the JRC4558DD in favor of a JRC4558D or Burr Brown chip?

Thanks
Ricey

[diggum12]

Ricey, when he says cheaper all he is referring to is cost.  At least he had better be, because they sound identical.  I can't tell a lick of difference, and I'm VERY picky about OpAmps.  Be very careful to not "follow the herd" when it comes to 4558 chips, because they all sound the same.  A 20 cents RC4558P from Digikey sounds exactly like a NOS JRC4558D that you buy off of Ebay for $6.00! 

I don't think that's what Monte's saying, but you're safe with any 4558 IMHO.  Yes, a Burr Brown does sound slightly different, a bit smoother I believe. 

Hope that helps!

[Hammer]

Brian

The mods I have say to use a .22 cap for C4 to reduce mids.
There's a massive volume drop and it becomes very bassy with this. Should it be a .022 as mentioned above ?

Also... what does the R9 mod do ?

Thanks

[brian wampler]

Brian:

Over on Monte Allum's site, he states that the chip in the stock SD-1 is a JRC4558DD, which he asserts is a cheaper version of the JRC4558D found in a Tubescreamer.  Is this true?  If so, what would be the effect on the mod you recommended above if I also  switched out the JRC4558DD in favor of a JRC4558D or Burr Brown chip?

Thanks
Ricey

Diggum is right on the money...I wouldn't mess with the opamp unless you are having problems. IC changes are hyped up so much it is pitiful. In this type of circuit the change is minimal.

bw

[brian wampler]

Brian

The mods I have say to use a .22 cap for C4 to reduce mids.
There's a massive volume drop and it becomes very bassy with this. Should it be a .022 as mentioned above ?

Also... what does the R9 mod do ?

Thanks

C4 is part of a low pass filter, if you change to a .22uf you'll need to boost the output after this, which is what R9 is going to do. Increase r9 as much as you need to to get your output level back up.

Hope that helps!

Thanks,
Brian

[Hammer]

Thanks Brian.
Is C4 the best way to flatten mids ?

[brian wampler]

Thanks Brian.
Is C4 the best way to flatten mids ?

not the best way, but the *easiest* way to sort of flatten the mids without doing a major circuit overhaul. You could actually install a gyrator circuit (simulated inductor, or like a one band eq circuit) and do it that way but it is a ways more advanced for many DIY'ers. The advanced book talks about this quite a bit...
Hope that helps!

bw

[Hammer]

Thanks for the help Brian.
I have all the books, but I'm still playing catch up with the knowledge to use the info 
I'm really liking my SD-1 at the moment - it blows most my Boutique pedals away !!

[Matybigfro]

Yes, it sure can exist...I would do these changes:
R5: 1K
D4: LED
C3: .47uf
R6: 2.2k or 1.5k if you need less bass



are these mods to acchieve the above sounds to the already fallclone modded pedal or to the stock sd-1 pedal

[Steve L]

I tried the SD-1 and DS-1 Boss pedals stock , there was a certain dirt noise in them I thought may in the OP amp so I did not keep them for modding. Allums changes the op amps on his Boss mod .  The op's in the tubescreamers , Route 66 and the Jacques tube blower all  use the same old 4558  and sound outstanding when modded. Will the mod without an OP amp change in these Boss pedals get you that quality of sound. There may be different ways get great sound from that Boss pedal. Is it that both approaches may work well?
 Maybe someday we will see  Mod Pedal shootouts with awards.
 Brians modded Jacques Tube Blower is the best overdrive I have ever heard, His modded TS 9 DX Turbo Screamer is awesome too. If you can get a inexpensive Boss to sound close to those that would be like a grandslam winner in the 9th.

[brian wampler]

I tried the SD-1 and DS-1 Boss pedals stock , there was a certain dirt noise in them I thought may in the OP amp so I did not keep them for modding. Allums changes the op amps on his Boss mod .  The op's in the tubescreamers , Route 66 and the Jacques tube blower all  use the same old 4558  and sound outstanding when modded. Will the mod without an OP amp change in these Boss pedals get you that quality of sound. There may be different ways get great sound from that Boss pedal. Is it that both approaches may work well?
 Maybe someday we will see  Mod Pedal shootouts with awards.
 Brians modded Jacques Tube Blower is the best overdrive I have ever heard, His modded TS 9 DX Turbo Screamer is awesome too. If you can get a inexpensive Boss to sound close to those that would be like a grandslam winner in the 9th.

honestly...there is SOOOO much hype around opamp changes that I don't change them unless one happens to be particularly noisy or something (this is in the case of dirt pedals - other types of pedals are exempt from my opinion here. ). I think Monte is a great guy but I honestly think that sometimes alot of the newer modders are just changing things because "everyone else does". The change of an opamp in a overdrive/distortion/or fuzz pedal is going to be very subtle.

Hope that helps!

bw

[Hammer]

There were several different chips fitted to the SD-1 from the factory, so Monte's aim might be just to ensure consistency when modded.
I have an SD-1 with a combination of Brian's mods that really sounds HUGE - the diodes being the most important change.
I've tried a variety of chips in it, and the differences are subtle, but detectable with some chips.
Generally I would say you cannot go wrong with 4558D, 4558DD, 4558P, 4559. The NE5332 also always sounds good to me.
Some of the better, more hi-fi chips will sound different... not to my liking, but some people like them.

Jack Orman has written an article about what causes the differences between opamps in a TS type circuit - and proposed a simple cure. The article is on his CD which he sells, so I'm not sure I can put it here but it's a good read. It's called "Taming the TS op-amp".